Dust control system

ABSTRACT

A method and an apparatus for reducing dust is disclosed for use with a working machine which is adapted to fragment material from a working surface and includes at least one partially confined space in which dust occurs. A liquid capable of binding dust is provided and the liquid is sprayed into the partially confined space to trap dust particles generated during fragmentation of the material form the working surface.

TECHNICAL FIELD

[0001] The present invention relates generally to the field of dustcontrol, and more particularly to a method and apparatus for controllingdust generated by a working machine such as a cold planer.

BACKGROUND

[0002] Industrial working machines often produce finely fragmentedmaterial or dust as an unwanted byproduct of the working process. Forexample, road working machines commonly known as cold planers or roadscarifiers comprise a working device, e.g. a milling drum to remove, forexample, a surface layer from a road to be repaired. The material to beremoved is fragmented or broken up into small pieces by the workingdevice and then transported to another location for collection and/orfor reuse. During this fragmentation and transport process the broken upmaterial generates large amounts of dust particles. This dust is anundesirable byproduct of the road working process.

[0003] EP 0 971 075 A1 discloses one attempt to handle dust developedduring grinding of road surfaces, by providing, on a scarifier, a dusthandling device. The dust handling device comprises a housing at leastpartially enclosing the milling drum and defining a suction area, asuction fan and a suction duct connecting said suction area and saidsuction fan. The suction fan discharges the dust containing air suckedaway from the working space above the milling drum through a filter. Thefiltered air is then discharged and the collected dust powder isdischarged to a different location. This system has the disadvantage ofbeing complex, large in size, and expensive to implement. It alsogenerates additional noise, reduces available machine working horsepowerbecause of power consumed by the fan, and requires frequent maintenanceof the air filter.

[0004] U.S. Pat. No. 4,325,580 is generally directed to a roadwayplanning apparatus, and discloses a water spray system used for cleaninga road mill and also for controlling dust. Water is alternativelydirected either to cleanup hoses or to spray bars disposed withinplaning and reclaiming assemblies. Specifically, water is sprayeddownward on a cutter drum to cause dirt and dust generated by thecutting process to coalesce. Water is also sprayed on the inner ornon-transport surface of transport conveyor belts to wash dirt and dustfrom the belts that might otherwise accumulate around the belt rollers.This system uses only water as a sprayed agent which is not particularlyeffective at binding dust particles, and this system fails to addressareas of a road mill where a large amount of dust is generated, inparticular, the transport surfaces of the conveyor belts.

[0005] In the mining industry, it is known to spray the mined materialwith water to avoid the generation of dust while processing andtransporting the mined material, e.g. coal. There are also suggestionsto add an agent to the sprayed water to reduce the surface tension ofthe water so it may form smaller droplets during spraying, thusincreasing the sprayed surface area. As disclosed in U.S. Pat. No.6,124,366, examples for such agents available on the market are Dustcon™and Dustclean™ produced by NALCO Chemical Company, Naperville, Ill.,USA. Dustcon™ and Dustclean™ are so called dust binding agents having anorganic lemon or citrus fruit basis and are both biodegradable and notharmful to the environment. In application in coal mines, the dustbinding agent is mixed with the water being sprayed on the mined coal toreduce the generation of dust. The amount of required spray water may beremarkably reduced upon addition of the dust binding agent.

[0006] The instant invention is directed toward providing an improveddust control system and overcoming one or more of the problems set forthabove.

SUMMARY OF THE INVENTION

[0007] The present invention provides a method and an apparatus forreducing dust during operation of a road working machine like a coldplaner. In accordance with the method and the apparatus of theinvention, the dust produced by the generation and transport offragmented material in the road working machine is effectively trappedand removed from the air.

[0008] In one aspect of the invention, a method of reducing dustproduced by a work machine which is adapted to fragment material from aworking surface and includes at least one partially confined space inwhich said dust occurs, includes the steps of providing a liquidincluding a dust binding agent and spraying the liquid into thepartially confined space.

[0009] The invention also provides a road working machine having aworking device adapted to fragment a working surface. The road workingmachine includes a water source connected to a pump which in turn isconnected to at least one outlet. The water source includes a dustbinding agent, and the outlet is directed at the fragmented materialfrom the working device.

[0010] According to another aspect of the invention, an apparatus forreducing dust is provided. The apparatus is adapted to be mounted on aroad working machine having a working device adapted to fragment aworking surface. The apparatus includes a water source connected to apump which in turn is connected to at least one outlet. The water sourceincludes a dust binding agent and the outlet is adapted to be mounted toa portion of the working machine so as to be directed at the fragmentedmaterial from the working device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows a schematic side view of a road working machine;

[0012]FIG. 2a shows a schematic arrangement of parts of an embodiment ofan apparatus for reducing dust in a road working machine in accordancewith the invention;

[0013]FIG. 2b shows a detail of a part of the apparatus of FIG. 2a in adifferent view.

[0014]FIG. 3 shows another part of an apparatus for reducing dust in aroad working machine.

DETAILED DESCRIPTION

[0015]FIG. 1 shows schematically a road working machine 1 in a sideview. The road working machine 1 includes a machine frame 2 and tractionsupports 3 for supporting the machine frame 2 and moving it along thedriving direction. A driver's seat 4 or operator's station is locatedgenerally above a working device 5 supported at a central position onthe machine frame 2 and schematically indicated by dashed lines.

[0016] The working device 5 is adapted to remove material from a workingsurface 6 and may be a milling drum equipped with grinding tools (notshown) which fragment the surface layer of the working surface 6 whenthey come in contact therewith. Around the working device 5, there isprovided a housing 7 defining a working space 8 of the working device 5.Dust and other debris material generated during the removal of thesurface material, i.e. the fragmentation of the working surface, aregenerally confined in the working space 8 by the housing 7.

[0017] During operation, the working device 5 gets hot and needs to becooled. Cooling is typically achieved by spraying cooling water suppliedfrom a water tank 9 carried by the working machine 1 onto the workingdevice 5, e.g. the milling drum. To this end, a spraying means (notshown) is provided inside the housing 7 of the working device.Generally, this spraying means comprises nozzles which are adapted togenerate a fan shaped cooling water jet which is directed onto theworking device 5.

[0018] In a typical embodiment, conveyor means 10 in front of theworking device 5 are provided to transport the fragmented materialproduced during operation of the working device 5 away from the workingspace 8 and to a collecting location, e.g. to a loading platform of atruck (not shown) driving in front of the working machine 1. Theconveyor means 10 may consist of a lower conveyor belt 11 and an upperconveyor belt 12. As indicated in FIG. 1, the upper conveyor belt 12 maybe moved or pivoted relative to the lower conveyor belt 11 in a verticaland horizontal direction so as to properly adjust the conveyor means 10with regard to the collection location (not shown). Preferably, theupper conveyor 12 may also be foldable so as to reduce its total lengthduring transportation of the working machine 1.

[0019] The upper conveyor belt 12 may be also moved towards the lowerconveyor belt 11 so as to properly load the transported material fromthe lower conveyor belt 11 onto the upper conveyor belt 12. Preferably,the conveyor means 10 are covered by a hood structure 13 on the upperconveyor belt 12 and a cover structure (not shown) connected to themachine frame 2 in the area of the lower conveyor belt 11. The hoodstructure 13 joins to the cover structure of the lower conveyor belt 11when a lower end 14 of the upper conveyor belt 12 is moved towards anupper end 15 of the lower conveyor belt 11 and positioned above thesame.

[0020]FIGS. 2a and 2 b show schematically a detail of the conveyor means10 in the area of the upper end 15 of the lower conveyor belt 11 and thelower end 14 of the upper conveyor belt 12. The hood structure 13, themachine frame 2 and the cover structure of the lower conveyor belt 11form a space 20 more or less confined to prevent the dust generated bythe fragmented material from immediately escaping to the surroundingenvironment.

[0021] In a preferred embodiment, in the area of the partially confinedspace 20, a dust handling apparatus 30 is installed on the workingmachine 1 at the upper end 15 of the lower conveyor belt 11 and at thelower end 14 of the upper conveyor belt 12. The dust handling apparatus30 includes a liquid supply system 32 and a plurality of outlets 141,142. The liquid supply system 32 supplies a liquid under pressure to theoutlets 141, 142.

[0022] The outlets 141, 142 are realized as nozzles mounted on wallstructures around the conveyor belts 11, 12. The wall structures mayinclude side walls extending from the conveyor belts, parts of the coverstructure of the lower conveyor belt 11, parts of the hood structure 13of the upper conveyor belt 12, and/or parts of the machine frame 2. Asindicated in FIG. 2a, the outlets 141, 142 direct the liquid onto thefragmented material conveyed on the lower and upper conveyor belts 11and 12 preferably in the form of a widely dispersed spray, which is,more preferably, conically shaped. The liquid in the preferred TMembodiment includes water mixed with a dust binding agent, e.g. Dustcon,in a predetermined mixture ratio. Appropriate mixture ratios arerecommended by the manufacturer of the dust binding agent.

[0023] The liquid supply system 32 comprises a plurality of hoses ortubings 201 to 210, 216, 219 and 220 forming a network including a firstand a second distributor means 211 and 221, a plurality of couplings 315to 318, and a plurality of T-connectors 314. Hoses 203 and 207 areconnected to the first distributor means 211 receiving the water mixedwith the dust binding agent as indicated by the arrow 212. The hose 203distributes the liquid via couplings 316, 315 and T-connectors 314 tothe hoses 201, 202 and 204 wherein in turn the hose 201 is connected toan upper one of the outlets 141, the hose 202 is connected to a middleone of the outlets 141 and the hose 204 is connected to a lower one ofthe outlets 141 in FIG. 2a. The outlets 141 direct the conically shapedspray of the water mixed with the dust binding agent onto the fragmentedmaterial transported on the lower conveyor belt 11.

[0024] The hoses 207 connect the first distributor 211 with the seconddistributor 221 to which they are coupled on a side surface of thesecond distributor 221 by couplings 318. On an opposite side surface ofthe second distributor 221 hoses 205, 216, 219, and 220 are coupled tothe second distributor 221 via couplings 317 and T-connectors 314. Thehoses 206 and 208 are coupled to the remaining side surfaces of thesecond distributor 221, and, as shown in FIG. 2b, the hoses 209 and 210are coupled to a bottom surface of the second distributor 221 byrespective couplings 317. The upper surface of the second distributor221 is mounted to a part of the machine frame 2.

[0025] The hoses 205, 216 and the hoses 206, 209 direct the liquid torespective outlets 142 in the form of nozzles mounted on opposite sidesof the lower conveyor belt 11. The hoses 208, 210 provide respectiveoutlets 142 at the upper end 15 of the lower conveyor belt 11 with theliquid consisting of water mixed with the dust binding agent, and thehoses 219, 220 supply this mixture to respective outlets 142 mounted inthe area of the lower end 14 of the upper conveyor belt 12. Thus, thewater mixed with the dust binding agent is sprayed onto the fragmentedmaterial in the area where it is discharged from the lower conveyor belt11 onto the upper conveyor belt 12, whereby the outlets or nozzles 142form a conically shaped sprayed mist of fine water droplets which act totrap the dust particles generated by the fragmented material.

[0026]FIG. 3 shows an embodiment of a part of the supply system 32 (alsocalled water source) which provides the water mixed with the dustbinding agent pressurized to the first distributor 211 in FIG. 2a. Inthis embodiment, the water is directly mixed with the dust bindingagent, and this mixture is stored in the water tank 9 of FIG. 1.

[0027] The water tank 9 is provided with an outlet port (not shown)which is connected via a shut off tap or valve 426 and a supply line 423to a filter 422. The filter 423 in turn is connected via another line428 to a pump 438. The pump 438 pressurizes the liquid received on theline 428. An outlet (not shown) of the pump 438 is connected via line437 with the first distributor 211, as indicated by the arrow 212.

[0028] The pump 438 is hydraulically driven and to this end the pump 438is supplied with hydraulic fluid via hydraulic lines 439. The pump 438is cooled by the liquid being passed therethrough and a bypass line 440directs the liquid back to the tank 9 in case it is disconnected or shutoff from the first distributor 211.

[0029] As mentioned above, the spraying system provided in the housing 7around the working device 5 (see FIG. 1) for cooling the working device5 is connected to the water tank 9 containing the mixture of water anddust binding agent. Thus, in this embodiment, the cooling water sprayedonto the working device 5 has also an improved dust capture capabilityand helps to reduce the amount of dust generated in the working space 8.

[0030] In a different embodiment, the water and the liquid dust bindingagent are stored at separated storing locations, i.e. the water isstored in the tank 9 and the dust binding agent is stored in a dustagent container (not shown). The dust binding agent container isprovided with an outlet which is connected to a liquid supply linecoming from the water tank 9. This connection can be made whereverconvenient, for example just after the filter, or just before the pump438 or even after the pump 438. Preferably, the dust binding agent isfed into the liquid supply line by a metering device (not shown) tocontrol the amount of dust binding agent mixed in the water supplied onthe supply line. This arrangement helps to better control theconsumption of the dust binding agent and to apply it only to selectedlocations, e.g., the area where the outlets 141 and 142 of the dusthandling apparatus 30 are mounted on the working machine 1.

[0031] It is to be understood that the housing 7 of the working device 5may be equipped with nozzles connected to the supply system for thewater and dust binding agent mixture and capable of generating a widelydispersed spray of the liquid to more effectively trap the dustgenerated by the fragmentation of material by the working device 5directly in the working space 8.

INDUSTRIAL APPLICABILITY

[0032] In operation of the working machine 1, the material of theworking surface 6 is fragmented by the working device 5 and isaccompanied by the generation of a high amount of dust particles andsmoke. This dust and smoke which is more or less contained in thehousing 7 around the working device 5 moves up the lower conveyor belt11. In case no preventive measure is taken, the dust may just escape tothe environment surrounding the working machine 1.

[0033] The liquid mixture of water and dust binding agent sprayed ontothe fragmented material has a high capability of entrapping dustparticles generated by the fragmented material produced by the millingoperation of the working device 5 on the working surface 6. In thepreferred embodiments described above, the occurrence of dust issignificantly reduced either in the working space 8, or in the area ofthe lower conveyor belt 11 where the fragmented material is loaded onthe upper conveyor belt 12, or at both locations.

[0034] The widely dispersed spray pattern, which is in the preferredembodiment a conically shaped spray, helps to increase the sprayed areaand to generate a fine mist of droplets of the dust binding agentmixture.

[0035] Thus, eventually the dust emerging from the working machine 1,especially at the discharge end of the conveyor means 10, is remarkablyreduced and is less of a problem for the operators working on and aroundthe machine 1. The dust binding agent used is preferably biodegradableand environmentally not harmful.

[0036] In accordance with the invention an improvement of the dusthandling is achieved by, generally speaking, spraying generated dust aspossible or practical. This is best realized by spraying the mixtureonto the fragmented material at a location where the dust can not easilyescape to the surrounding environment. In this respect, the meaning ofconfined space is to be understood as an at least partially confinedspace or a space in which the dust is channeled. Also, the exact choiceof where the outlets or spray heads are located and how many areutilized depends on the particular configuration of the working machinewhich might vary from case to case and is not necessarily limited to theconfiguration of the working machine 1 of FIG. 1.

[0037] Further, the existing spray system for cooling the working device5 may be also used to spray the water and dust binding agent mixtureinto the working space 8. In this case, and for an improved dusthandling, it is sufficient to simply add the dust binding agent to thewater tank 9 of the working machine 1.

[0038] It is clear, that upon reading the foregoing specification, manyalternatives, modifications and changes may be realized by the manskilled in the art. Therefore, the scope of the present invention is notintended to be limited by the embodiments described above in somewhatdetail, but it is to be defined by the appended claims and theequivalents thereof.

What is claimed is:
 1. A method of reducing dust produced by a workingmachine adapted to fragment material from a working surface, saidworking machine including a tank for holding a liquid, an associatedliquid supply system, and at least one partially confined space in whichsaid dust occurs, comprising the steps of: providing a liquid includinga dust binding agent, and spraying said liquid into said at least onepartially confined space.
 2. The method of claim 1, including the stepof combining said dust binding agent with water.
 3. The method of claim2 wherein said dust binding agent is adapted to lower the surfacetension of water.
 4. The method of claim 3, wherein said dust bindingagent is based on an organic citrus ingredient and is biodegradable. 5.The method of claim 2, wherein said water is supplied from said tank viasaid liquid supply system, and said combining step includes the step ofcontrollably adding said dust binding agent to said water at a selectedlocation along said liquid supply system.
 6. The method of claim 2,wherein said combining step includes the step of mixing said water andsaid dust binding agent in said tank.
 7. The method of claim 1, whereinsaid liquid is sprayed in a widely dispersed spray pattern into saidpartially confined space.
 8. The method of claim 1, wherein saidpartially confined space includes a space above a conveyor adapted toconvey the removed material to a collection location.
 9. The method ofclaim 1, wherein said working machine includes a working device adaptedto fragment said working surface, and wherein said partially confinedspace includes a working space around said working device.
 10. A roadworking machine having a working device adapted to fragment a workingsurface, comprising: a source of water connected to a pump connected toat least one outlet, said water including a dust binding agent, and saidat least one outlet being directed at working surface materialfragmented by said working device.
 11. A road working machine, as setforth in claim 10, wherein said source of water includes a tank and aliquid supply system adapted to connect said tank and said at least oneoutlet; and wherein said source of water further includes a dust bindingagent supply means connected to said supply system and adapted to add adust binding agent to the water supplied by said liquid supply systemfrom said tank.
 12. A road working machine, as set forth in claim 11,wherein said dust binding agent supply means includes a metering deviceadapted to control the amount of said dust binding agent being added tothe water.
 13. A road working machine, as set forth in claim 10, whereinsaid source of water includes a tank and a liquid supply system adaptedto connect said tank and said at least one outlet, said tank containingwater mixed with said dust binding agent.
 14. A road working machine, asset forth in claim 10, wherein said dust binding agent lowers thesurface tension of water.
 15. A road working machine, as set forth inclaim 14, wherein said dust binding agent is based on an organic citrusingredient and is biodegradable.
 16. A road working machine, as setforth in claim 10, wherein said at least one outlet is directed into apartially confined space of said working machine containing saidfragmented material, said partially confined space including a spaceabove a conveyor adapted to convey the fragmented material to acollection location.
 17. A road working machine, as set forth in claim10, wherein said partially confined space includes a working spacearound said working device.
 18. A road working machine, as set forth inclaim 10, wherein said at least one outlet includes at least one nozzleadapted to generate a widely dispersed spray of said water mixed withsaid dust binding agent and directed onto said fragmented material. 19.An apparatus for reducing dust, said apparatus being adapted to bemounted on a road working machine having a working device adapted tofragment a working surface, comprising: a water source connected to apump connected to at least one outlet, said water source including adust binding agent and said at least one outlet being adapted to bemounted to a portion of said working machine so as to be directed atsaid fragmented material from said working device.
 20. An apparatus, asset forth in claim 19, wherein said water source includes a tank and asupply system adapted to connect said tank and said at least one outlet;and wherein said water source further includes a dust binding agentsupply means connected to said supply system and adapted to add saiddust binding agent to the water supplied by said supply system from saidtank.
 21. An apparatus, as set forth in claim 20, wherein said dustbinding agent supply means includes a metering device adapted to controlthe amount of said dust binding agent being added to the water.
 22. Anapparatus, as set forth in claim 19, wherein said water source includesa supply system adapted to connect a tank provided on said road workingmachine and said at least one outlet; said tank containing water mixedwith said dust binding agent.
 23. An apparatus for reducing dust, saidapparatus being adapted to be mounted on a machine having at least onepartially confined work space, comprising: a source of water containinga dust binding agent; and at least one liquid spray outlet connected tosaid source and disposed in said work space.
 24. An apparatus, as setforth in claim 23, including a tank containing water mixed with saiddust binding agent.
 25. An apparatus, as set forth in claim 23,including a dust binding agent supply means adapted to combine said dustbinding agent with said water, said dust binding agent supply meanshaving a metering device adapted to control the ratio of said dustbinding agent to said water.
 26. An apparatus, as set forth in claim 23,wherein said machine includes at least one conveyor having a transportsurface and said at least one partially confined work space includes aspace above said at least one conveyor transport surface; and whereinsaid at least one liquid spray outlet is located at a positionsufficient to direct said water and dust binding agent onto said atleast one conveyor transport surface.